Number of bridges in Minnesota

Believe it or not, there are more than 20000 bridges in Minnesota. Keep in mind the fact that the bridges in Minnesota are structured in 8 categories: bridges on the National Register of Historic Places in Minnesota?, bridges in Minneapolis, Minnesota, bridges in Saint Paul, Minnesota, covered bridges in Minnesota, pedestrian bridges in Minnesota, railroad bridges in Minnesota, road bridges in Minnesota, toll bridges in Minnesota.? Specialists consider the fact that there are 1,191 troubled bridges in Minnesota.